Prostate cancer is the most common lethal tumor among US males yet little is known about its causative mechanisms. This study proposes to examine how glycosylation of sex hormone binding globulin (SHBG) affects steroid hormone signaling in prostate cancer. We will define the impact of SHBG glycosylation, including the D327N SHBG polymorphism, on steroid hormone associated prostate cancer risk and disparity in African and Caucasian Americans. Protein glycosylation is critical for interaction of prostate cells with its environment. We will evaluate how glycosylation of SHBG affect the distribution of the protein between plasma and tissue and how this affects disease development. The quantification of the SHBG glycoforms will be achieved by novel LC-MS assays. In addition, we will comprehensively summarize the impact of polymorphisms on N-glycosylation in the human proteome. Our hypothesis is that prostate cancer risk and progression are related to the variability in the glycosylation of SHBG. Our objective is to perform quantitative mass spectrometric assays of SHBG glycosylation in conjunction with measurement of steroid hormones. We will select men for phenotypic characterization by genotyping of a case control population with 50% African American representation. In addition, we will genotype a case series for which both serum and tissue are available. Steroid hormones will be measured by GC-MS. We will analyze the SHBG glycoforms and steroid hormones at the tissue level and in the circulation. The study is expected to fill important gaps in our understanding of prostate cancer etiology and progression. The analysis of SHBG glycoforms will provide new information on the biological factors underlying prostate carcinogenesis. The results are expected to improve prostate cancer prevention, detection and intervention strategies.